1. Field of the Invention
The present invention relates to a light source apparatus and an image projection apparatus including the light source apparatus for projecting an enlarged image.
2. Description of the Related Art
Recently, there has been proposed to use a laser as a light source for an image projection apparatus such as a projector or the like. A commercially available rear projector where a laser is used as the light source is provided, for example. For a front projector, a laser is used in combination with a fluorescent material as the light source has been actualized because of a problem of speckling in a projected image or the like.
When using a laser as the sole light source of the image projection apparatus, repeatability of color, luminous efficacy, efficiency of utilization of light or the like can be improved. Further, as the laser is a point light source (or a parallel beam), it is easy to design the optical system, mixing of colors is easy, and the number of apertures (Numerical Aperture (NA)) of a projector lens in the image projection apparatus can be reduced.
Here, when solely using the laser as the light source of the image projection apparatus, it is an important problem to obtain sufficient amount of light. In order to solve this problem, examples where plural lasers are densely placed in a matrix form or in two-dimensional form on a plane are provided (Patent Document 1 and Patent Document 2, for example).
However, if plural lasers are densely provided, there is another problem with how efficiently those lasers are cooled. By densely providing the large number of lasers, the size of the image projection apparatus can be reduced. However, in such a case, it becomes more difficult to radiate heat so that a cooling unit with a larger power may be necessary. On the other hand, in order to efficiently cool the lasers, the lasers may be provided with longer intervals to each other. However, in such a case, the size of the image projection apparatus becomes larger as well as the incident angles of the lights to be injected into a rod integrator of the image projection apparatus may become larger so that an optical system may not function well.